This invention relates to a cassette loading/unloading apparatus for cassette tape recorder.
In a slot-in type a cassette tape recorder utilizing a toggle spring, a cassette is pushed into a cassette holder against the biasing force of the toggle spring at cassette insertion until it reaches the neutral point of the toggle spring. When the neutral point of the toggle spring is passed, the biasing force of the toggle spring acts so as to draw the cassette in the cassette holder, and thus the cassette is instantly drawn into the cassette holder. The stroke of the cassette terminating at the neutral point of the toggle spring is called the pushing-in stroke, while the stroke starting at the neutral point is called the drawing-in stroke. The length of each stroke is proportional to the biasing force produced in the toggle spring. If the drawing-in stroke is large, the biasing force of the toggle spring to act after the cassette is drawn in the cassette holder may be set at a high level, so that the cassette can be loaded securely. If the pushing-in stroke is large, on the other hand, the biasing force of the toggle spring to act as an ejecting force at cassette ejection may be set at a high level, so that the cassette ejection can be ensured.
In general, the toggle spring is so disposed that the pushing-in and drawing-in strokes are equal in length. There are known two types of cassettes; compact cassette and micro cassette whose surface area is approximately 1/4 of that of the compact cassette. With the compact cassette, which is relatively large-sized, both strokes can generally be large enough to ensure both cassette insertion and ejection. With the micro cassette, however, neither of the strokes can be large due to the limited cassette size. In some cases, it is difficult to make the strokes large enough even with the compact cassette because of the positional relations with other members and limited space.
Generally known is a slot-in type cassette tape recorder in which a toggle spring is so disposed that the drawing-in stroke is larger than the pushing-in stroke. Since the pushing-in stroke is small, however, the ejecting force provided by the toggle spring cannot be great in the ejecting stroke. There has not yet been provided a cassette loading/unloading apparatus adapted for making up for the ejecting force. In an apparatus disclosed in Japanese Patent Disclosure No. 146,651/80, a toggle spring is so disposed that the drawing-in stroke is larger than the pushing-in stroke. In the ejecting stroke, when the ejecting plate is depressed, a knife edge rocks and abuts against a slider to press the same in the cassette ejecting direction, that is, outward. When the slider moves after passing the neutral point of the toggle spring, however, the biasing force of the toggle spring acts as an ejecting force. Accordingly, the slider tends to go away from the knife edge, so that it is hard to apply an ejecting force from the knife edge to the slider. Thus, the slider cannot be subjected to a great ejecting force.
Staar and counter-Staar type cassette tape recorders are known as slot-in type cassette tape recorders.